On 20/07/17 13:22, Peter Zijlstra wrote: > On Thu, Jul 13, 2017 at 07:02:37PM -0700, Saravana Kannan wrote: >> In all Qualcomm chipsets (well, at least the ones that have been used in >> Android devices so far), we can switch the frequency of any CPU from any >> other CPU. If we can do that even without fast switching, why wouldn't any >> theoretical fast switching be incapable of supporting this? Is this a >> limitation specific to x86 that we are assuming all architectures and >> platforms are going to have? > > So the typical implementation of fast switching we're thinking of is the > CPU writing the DVFS request into a machine register. Now machine > registers are typically per logical CPU. >
But, if ARM decides to architect and move to it to a system/machine register, we will end up with the same limitation :( IMO. For now with SCMI kind of interface, there's no such limitation as yoalready mentioned in the follow up email. -- Regards, Sudeep
